docs: def get_requires(self, ignored=tuple()):
          """ a map of requirements to what requires it. ignored is an
          optional list of globbed patterns indicating packages,
          classes, etc that shouldn't be included in the provides map"""
  
          if self._requires is None:
              self._collect_requires_provides()
  
          d = self._requires
          if ignored:
              d = dict((k, v) for k, v in d.items()
                       if not fnmatches(k, *ignored))
          return d